Measurement of Renal Pelvic Pressure In Vivo While preparing for the SMP, the open-ended ureteric catheter, which had been inserted into the renal collecting system retrogradely, was connected to the invasive blood pressure channel of patient monitor with a baroceptor. The baroceptor was fixed onto the horizontal plane of renal pelvis; after a zero adjustment, the measurement of renal pelvic pressure was in session. A computer collected the renal pelvic pressure data each second. Any factor that caused a high renal pelvic pressure was noticed .